"Obama's Wars" marks the 16th book by Woodward, 67, a Washington Post associate editor. Woodward's reporting with Carl Bernstein on the Watergate coverup in the early 1970s led to their bestselling book "All the President's Men."

Among the book's other disclosures:

-- Obama told Woodward in the July interview that he didn't think about the Afghan war in the "classic" terms of the United States winning or losing. "I think about it more in terms of: Do you successfully prosecute a strategy that results in the country being stronger rather than weaker at the end?" he said.

-- The CIA created, controls and pays for a clandestine 3,000-man paramilitary army of local Afghans, known as Counterterrorism Pursuit Teams. Woodward describes these teams as elite, well-trained units that conduct highly sensitive covert operations into Pakistan as part of a stepped-up campaign against al-Qaeda and Afghan Taliban havens there.

-- Obama has kept in place or expanded 14 intelligence orders, known as findings, issued by his predecessor, George W. Bush. The orders provide the legal basis for the CIA's worldwide covert operations.

-- A new capability developed by the National Security Agency has dramatically increased the speed at which intercepted communications can be turned around into useful information for intelligence analysts and covert operators. "They talk, we listen. They move, we observe. Given the opportunity, we react operationally," then-Director of National Intelligence Mike McConnell explained to Obama at a briefing two days after he was elected president.

-- A classified exercise in May showed that the government was woefully unprepared to deal with a nuclear terrorist attack in the United States. The scenario involved the detonation of a small, crude nuclear weapon in Indianapolis and the simultaneous threat of a second blast in Los Angeles. Obama, in the interview with Woodward, called a nuclear attack here "a potential game changer." He said: "When I go down the list of things I have to worry about all the time, that is at the top, because that's one where you can't afford any mistakes."

-- Afghan President Hamid Karzai was diagnosed as manic depressive, according to U.S. intelligence reports. "He's on his meds, he's off his meds," Woodward quotes U.S. Ambassador Karl W. Eikenberry as saying.

'The cancer is in Pakistan'

Obama campaigned on a promise to extract U.S. forces from Iraq and focus on Afghanistan and Pakistan, which he described as the greater threat to American security. At McConnell's top-secret briefing for Obama, the intelligence chief told the president-elect that Pakistan is a dishonest partner, unwilling or unable to stop elements of the Pakistani intelligence service from giving clandestine aid, weapons and money to the Afghan Taliban, Woodward writes.

By the end of the 2009 strategy review, Woodward reports, Obama concluded that no mission in Afghanistan could be successful without attacking the al-Qaeda and Afghan Taliban havens operating with impunity in Pakistan's remote tribal regions.

"We need to make clear to people that the cancer is in Pakistan," Obama is quoted as saying at an Oval Office meeting on Nov. 25, 2009. Creating a more secure Afghanistan is imperative, the president said, "so the cancer doesn't spread" there.

The war in Iraq draws no attention in the book, except as a reference point for considering and developing a new Afghanistan strategy. The book's title, "Obama's Wars," appears to refer to the conflict in Afghanistan and the conflicts among the president's national security team.